The embodiment relates to an electromagnetic switching device, and more particularly to an electromagnetic switching device which can be assembled at high assembly accuracy by absorbing coupling tolerance in the process of assembling the electromagnetic switching device
An electromagnetic switching device is an electric switch device serving as a connection converter to switch on/off a main circuit according to tiny variation of input current. In the electromagnetic switching device, a contact point is moved by electromagnetic force so that current is applied or shut off.
FIGS. 1 and 2 are views showing an electromagnetic switching device according to the related art. The electromagnetic switching device includes a housing 10, and upper and lower assemblies 20 and 30 received in the housing 10.
The housing 10 includes top and bottom plates 11 and 13 having a substantially rectangular shape, and three side plates 12 interposed between the top and bottom plates 11 and 13. Since the housing 10 has only three side plates 12, an opening is formed at one side of the housing 10.
The upper assembly 20 includes a case 21 and an upper port 22 protruding from the case 21 to an outside.
The lower assembly 30 includes a case 31, a lower port 32 protruding from the case 31 to an outside, a coil 33 to which a current is applied through the lower port 32, a fixed core 34 included in the coil 33, a movable core 35 included in the fixed core 34, and a shaft 36 which performs a reciprocating motion together with the movable core 35.
Thus, the movable core 35 and the shaft 36 reciprocate up and down as power is intermittently supplied to the coil 33, so that a movable contact point coupled to the shaft 36 repeatedly makes contact with and is separated from a fixed contact point provided on the upper assembly 20.
According to a method of assembling the electromagnetic switching device of the related art, after the upper assembly 20 is coupled to the lower assembly 30 from the top of the lower assembly 30, the coupled upper and lower assemblies 20 and 30 are fitted into the housing 10, and then, epoxy is coated on an edge of the opening of the housing 10 to seal the housing 10.
In this assembling process, when an assembly tolerance occurs due to an increase in a height of the upper or lower assembly 20 or 30, the top surface of the case 21 of the upper assembly 20 pushes upward the top plate 11 of the housing 10, so that a gap is generated at the edge of the opening to be sealed.
Thus, the epoxy provided in the sealing process flows into the housing 10 through the gap, so that the failure rate is increased.